When we speak of the Holy Spirit – we are speaking of the Third Person of the Trinity – God the Spirit. Thus, the Holy Spirit in the NT is the same person as the Spirit in the Old Testament—different only in scope, not person or nature. Let’s review some of the important activities of the Spirit in the life of the believer:
The Spirit Indwells all Believers
JOHN 14:17: “That is the Spirit of truth, whom the world cannot receive, because it does not see Him or know Him, but you know Him because He abides with you and will be “in you”(cf. Rom. 8:9-11; 1 Cor. 3:16), In John 14:23. As the Spirit dwells with/in us, the Father and the Son dwells with/in us (cf. John 14:23; 1 John 1:3).
The Necessity and Benefits of the Holy Spirit
Dwelling Within Us
- That the Spirit indwells us shows that we are children of God, heirs of Him, and “fellow-heirs with Christ”—Romans 8:16–17: “The Spirit Himself testifies with our spirit that we are children of God, 17 and if children, heirs also, heirs of God and fellow heirs with Christ.”
- The indwelling Spirit gives us the wisdom and knowledge of the testimony of God and the crucifixion of the Son—1 Corinthians 2:12: “Now we have received, not the spirit of the world, but the Spirit who is from God, so that we may know the things freely given to us by God.”
- The indwelling Spirit leads and guides us—Romans 8:14: “For all who are being led by the Spirit of God, these are sons of God”; 1 John 4:4: “Little children, you are from God and have overcome them, for He who is in you is greater than he who is in the world.”
The Holy Spirit accomplishes regeneration in the hearts of sinners—John 6:63: It is the “Spirit who gives life; the flesh profits nothing.” Titus 3:5-7: “He saved us not on the basis of deeds which we have done in righteousness, but according to His mercy, by the washing of regeneration and renewing by the Holy Spirit, 6 whom He poured out upon us richly through Jesus Christ our Savior, 7 so that being justified by His grace – we would be made heirs according to the hope of eternal life.” Observe the emphasis of all three persons of the Trinity here. The same combination of words are found in Ezekiel 36:25-27 and Isaiah 44:3.
The Holy Spirit Sanctifies us at Conversion
1 Corinthians 1:2: “To the church of God which is at Corinth, to those who have been sanctified in Christ Jesus, saints by calling, with all who in every place call on the name of our Lord Jesus Christ, their Lord and ours” (cf. 1 Cor. 1:30-31; 6:11).
2 Thessalonians 2:13: “But we should [imperative mood] always give thanks to God for you, brethren beloved by the Lord, because God chose you from the beginning for salvation in sanctification of the Spirit and faith in the truth” (cf. 1 Pet. 1:1-2).
1 Peter 1:1-2: “Peter, an apostle of Jesus Christ, to those . . . who are chosen 2 according to the foreknowledge of God the Father, by the sanctifying work of the Spirit, to obey Jesus Christ and be sprinkled with His blood: May grace and peace be yours in the fullest measure.”
He is our Paraklētos (“Advocate”)
John 14:16: “I will ask the Father, and He will give you another Helper [paraklētos, lit., “advocate”], that He may be with you forever.”
The Holy Spirit Intercedes on Our Behalf
Romans 8:26-27: “The Spirit also helps our weakness; for we do not know how to pray as we should, but the Spirit Himself intercedes for us with groanings too deep for words; 27 and He who searches the hearts knows what the mind of the Spirit is, because He intercedes for the saints according to the will of God.”
The Holy Spirit installs Pastors
Acts 20:28: “Be on guard for yourselves and for all the flock, among which the Holy Spirit has made you overseers, to shepherd the church of God which He purchased with His own blood.”
The Holy Spirit Provides the Opportunities and the Results
Acts 1:8: “But you will receive power when the Holy Spirit has come upon you; and you shall be My witnesses both in Jerusalem, and in all Judea and Samaria, and even to the remotest part of the earth” (cf. Acts 8:29; Acts 10:19-20; Acts 13:2). The Holy Spirit also hinders evangelism (cf. Acts 16:6).
We Fellowship with the Holy Spirit in the context of the Triune God
2 Corinthians 13:14: “The Grace of the Lord Jesus Christ, and the love of God, and the fellowship of the Holy Spirit, be with you all.”
The Holy Spirit Gives Love to the Elect
Romans 15:30: “Now I urge you, brethren, by our Lord Jesus Christ and by the love of the Spirit, to strive together with me in your prayers to God for me.”
The Spirit enables us to carry out the Fruit of the Spirit in our Christian life
(cf. Gal. 5:22-23)
First note the starting context in the verse 16 (syntactical literal reading): “walk [‘behave, live’] by means of the Spirit [pneumati] and the lust of the flesh, never never, not even a possibility shall you gratify [‘fulfill, complete’].” The Spirit here in verse 16 is the Holy Spirit—the same Spirit that is spoken of in verses 18 and 22, thus, not the “spiritual” part of our nature, nor our spirit in union with the Spirit.
Galatians 5:22-23: “But the fruit of the Spirit, love, joy, peace, patience, kindness, goodness, faithfulness, 23 gentleness, self-control; against such things there is no law.” Interestingly, the term “fruit” (karpos) is singular, although there are nine characteristics. Grammatically, the term “love” (agapē) could have the semantic idea of the affixed English colon (“love:”). If this is the intended meaning, Paul would be indicating that the fruit of the Spirit is love, and the eight following characteristics is how Paul defines love. Thus, the fruit of love consists of joy, peace, patience, kindness, goodness, faithfulness, gentleness, self-control.
The Filling and Baptism of the Spirit
As seen, the indwelling of the Spirit refers to the eternal relationship (“in you”) we have with the Triune God at conversion—permanent and perpetual. Whereas “being filled,” as in Acts and Paul’s literature, was not permanent (and spontaneous in Acts). This particular phenomenon only occurred in special circumstances, usually producing boldness in the proclamation of the gospel—namely, as in Acts, the resurrection of Christ: “they were all filled with the Holy Spirit and began to speak the word of God with boldness” (Acts 4:31) and rarely did it result in tongues.
Further, being filled with/by the Spirit in Acts is not the same as the command to be filled with the Spirit in, for example, Ephesians 5:18. Notice that the verbal actions are present tense, in contrast to the single isolated accounts in Acts (which Paul could have achieved by using past tenses): “And do not get drunk with wine, for that is dissipation, but be filled [present imperative] en pneumati [lit., “by means of the Spirit”]. Syntactically, the preposition en (in, by, with) followed by the dative pneumati (“Spirit”) indicates instrument (means), not “content.” The two imperatives (commands), which are in the middle/passive voice, are, do not “get drunk” and “be filled” by means of the Spirit.
Thus, believers are to be filled (perhaps a reference to God’s moral attributes, or joy) by Christ (who is the agent) by means of the Spirit. Moreover, note the five participles in verses 19-21, “speaking to one another in psalms and hymns and spiritual songs, “singing,” “making melody,” “always giving thanks,” and “being subject to one another in the fear of Christ.” These are semantically participles of result—indicating the result of being filled by the Spirit. This filling is not connected with speaking in tongues. Further, Spirit filling in Acts was never commanded as in here in verse 18. In Acts, it was special inoculation or saturation of the Spirit for a particular work of service (similar to the Spirit’s activity of filling in the OT). Thus, Paul says that we must be continually filled with the Spirit, not just once or twice.
It was John the Baptist who first prophesied Spirit baptism: “I baptized you with water; but He [Christ] will baptize you with the Holy Spirit” (Mark 1:8). This prophecy was reiterated in Acts 1:4-5. Notice also that Mark 1:8 and Acts 1:5 contain the same syntactical construction– “baptized, en pneumati hagiō (lit., “with [the] Spirit Holy”). As seen in Ephesians 5:18, en (in, by, with) followed by a noun in the dative case (here, pneumati) can denote “means”—thus, “by means of the Spirit.” So according to this prophecy, Christ is the agent of the baptism (i.e., the one doing the action) and the Spirit is the instrument (i.e., the means, which Christ uses to perform the action)
When was this prophecy fulfilled? First, no exact time stamp is provided, but the first occurrences are in Acts. However, 1 Corinthians 12:13, does express a fulfilled action among all Christians: “For en heni pneumati [“by means of one Spirit”] we were all baptized into one body, whether Jews or Greeks, whether slaves or free, and we were all made to drink of one Spirit.” As in Mark 1:8; Acts 1:5; and Ephesians 5:18, we find en + dative indicating that the baptism was “by means of” the one Spirit (Christ being the agent). And note the double usage of pan (“all”) indicting that ALL Christians were baptized by the Spirit (at conversion), not merely a special class of so-called “anointed” or mature believers.
Spirit baptism is a gift promised by the Father – given first in Acts, which happens at conversion to ALL believers.
The Holy Spirit is active in our lives – He is our paraklētos, that is, He is called to be alongside of us. He regenerated us and caused us to be born again having sealed us for the day of redemption (cf. Eph. 1:13). And the same Spirit that hovered over the face of the waters (cf. Gen. 1:2), dwelled with David, came upon Samson and other judges and prophets, led Jesus into the wilderness, poured out upon all of His people at Pentecost, and filled Peter – lives with us and fills us—and helps us in our weaknesses. He provides us “fruit” to edify and move us to a life of love, relationship, and works of service – ultimately to glorify the Triune God.
 Paraklētos appears five times in the NT – John 14:16, 26, 15:26; 16:7 and once in 1 John 2:1 with in reference to the Son.
 See exegetical discussion of this passages in Daniel B. Wallace, Greek Grammar Beyond the Basics, 93,374-75,375